Method of stabilizing fats and oils and resulting product



Patented June 25, 1

METHOD OF STABILIZING FATS AND OILS AND RESULTING PRODUCT Ernest c. Crocker, Belmont, Mass, assignor to Arthur D. Little, Incorporated, Cambridge,

, a corporation of Massachusetts No Drawing. Application July 19, 1939,

Serial; no. 285,281

1s Claims. (Cl. 99-163 This invention relates to stabilization of anithe case. Also, that when used they will be in mal and vegetable fats and oils, and more parbetter condition, more satisfactory and safer ticularly to the inhibition or prevention of their than would be possible if they were not thus natural tendency to become rancid. stabilized and protected from oxidation and While various treatments of fats and oils are rancidiflcation. 3 known for the stabilization of the same against Typical of the edible fats which may be so oxidation, they are in many instances not suit treated is lard, which contains fatty acid comable for use with those fats or oils which are pounds of unsaturated structure, and is susedible and intended for human consumption. ceptible to ready oxidation by atmospheric con- This may be due to an inherent lack of suitability ditions, in consequence. no of the conditions or reagent used, or on account The various edible oils which may be treated of harmful chemical activity and .the like, or by the process may resemble the fats in combecause of extraneous undesirable effects such as position, in that they contain unsaturated fatty that of overcoming the natural flavor or odor of acids, or, as in the case of many of the vegethe fat or oiltreatedmrof imparting an undesirtable oils, and especially the essential oils, they 15 able flavor or odor thereto, on account of the may be typified by containing terpenes or retreatment or reagent itself. lated compounds. Such compounds are sus- It is accordingly an object of this invention to ceptible of "oxidation and/or polymerization provide a simple and safe method of stabilizing whereby they may not only lose their desirable edible animal or vegetable fats and oils, to procharacteristic properties but may acquire undem tect them from oxidation and rancidity, and at sirable properties such as an unpleasant taste the same time to leave unimpaired their general or odor, resembling that of turpentine or varfundamental suitabilities for food purposes and nish. These changes are well recognized in the also their desirable characteristic flavors and art of preparing and using essential oils, for odors. It is also an object to provide improved example, in hich the taste and odor are most 25 edible animal and vegetable fats and oils, both in important alifications. Upon aging, under respect of their natural qualities and in respect atmospheric conditions and especially in contact of their ability to preserve these properties with oxygen, the oils first lose their desirable through a prolonged period of time under the flavors or odors and then acquire the taste and normal oxidizing conditions of the atmosphere. odor of varnish. This type of rancidity is called 343 Other objects will appear from the following dis- "terpiness in the essential oils. closure. The stabilizing agent used in the present in- It is found that w -1: and vegetable fats and vention comprises the resinous compounds of oils, which are nat desirable for use in conlicorice root, which are insoluble in water but nection with or as a part of human food, but soluble in ethyl alcohol. These compounds form 85 which in many cases are susceptible to oxidaa brownish resinous substance and will be retion by the air under atmospheric conditions and ferred to herein, collectively, as licorice resin."

rapidly become rancid, may be protected from Licorice root, as heretofore treated for the exor stabilized against such changes by the additraction of its flavoring components,- has been tion thereto oi certain edible resins. These macerated and boiled with water or superheated may be dispersed through the tat or oil or dis= steam, the resulting liquor being separated and solved therein and in this form are effective to concentrated for use. The spent root from this accomplish the desired result. At the same time operation is generally either thrown away or they are substantially completely insoluble in utilized as a fibrous waste. More recently, such water and are characteristically without taste, spent fibers have been extracted with sodium 65 non-volatile, and without odor. carbonate solution in some instances and the Accordingly, the stabilized fat or oil possesses resulting soapy solution used in the extinguishers all of its desirable properties and at the same of the foaming type tosome extent, with carbon time is enabled to retain its natural properties dioxide gas.

for a prolonged period oi time, without deterio- It is now found, however, that if the spent 50 ration due to oxidation or rancidity. It follows, licorice roots or fibers, after the extraction with therefore, thattats and oils stabilized in this way water, are extracted with a suitable solvent they maybepreparedand then shipped for longer disyield a licorice resin, as above referred to.

tances or 1 stored in-"lai'ger quantities and for For example, if they are treated with relatively longer periodsof time than would otherwise be concentrated ethyl alcohol (e. g., above 60%) use:

the licorice resin is dissolved as a whole. This I have found to consist of a mixture of various alcohol soluble resins, which have in common the property of being relatively insoluble in water. I

To obtain the licorice resin for the purposes of this invention, the macerated fibrous root, preferably after preliminary extraction with hot water Aqueousethyl alcohol, of concentrations down to 60%, may be effectively employed and other solvents, such as methyl alcohol, isopropyl-alcohol, n-butyl alcohol, ethylene glycol mono-ethyl ether, etc., may be employed.

The total licorice resin as thus extracted may be obtained as suchby evaporating the solvent, and may be used in the resulting purified condition, or in some instances it may be used while in solution. It is substantially completely insoluble in water and is without taste or odor, and hence does notimpart any taste or odor to substances with which it is combined or mixed.

The licorice resin, as thus extracted, however, is not a single compound. I have found it to be made up of at least three'distinguishable and quite different components.

These components may be distinguished, inter se, as falling into three groups: (1) soluble in alcohol and benzene but not soluble in petroleum ether, (2) soluble in alcohol but not soluble in benzene or petroleum ether, and (3). soluble in alcohol, benzene and petroleum ether, respectively.

Of these components of the alcohol-soluble licorice resin, the first is a waxy resin, with a comparatively sharp melting point of about 50 (3.; the second is a resin that does not present a sharp melting point but softens with heat; and the third is an oil.

These may be separately recovered by treating the resin, which has been extracted by the procedure described above-and then evaporated to dryness, first with petroleum ether, for example. The resulting solution may then be separated and will contain the petroleum ether soluble component (3) leaving components (1) and (2) unaifected. The residue, which is insoluble inand unaffected. by petroleum ether, 'maythen be extracted with benzene which win, of course, dissolve the benzene soluble component (1) and the resulting solution can be readily separated from the benzene-insoluble component (2) which 7 component (2) as a residue. Upon separatingand evaporating the resulting benzene solution a soft solid, consisting of a mixture of components (1) and (3) will be left, and may be used as such or subsequently separated by extracting with petroleum ether, the soluble component (3) being I thereby dissolved, and removed.

The benzene soluble component (1) upon evaporation of the solvent. is a firm, light-colored waxy, resinous material of fairly definite melting point (about 50 C.) as described above, and is especially adaptable for the lmrposes of this inyention. Its ready solubility in fats and oils pro-.

tion therein. It is accordingly very effective for use as an anti-oxidant with such substances.

The alcohol-soluble, benzene-insoluble component (2) is firm and shellac-like, and while not so soluble in fats as the benzene soluble component (1), is readily enough dispersed or dissolved in essential oils, and is an eifective antioxidant therein.

The petroleum ether solublecomponent (3) which may be segregated from the alcohol-extractedlicoriceresinasabovedescribed orbya preliminary extraction of the spent licorice root with petroleum ether, is a liquid oil as already pointed out. It does not appearto be effective as an anti-oxidant to prevent oxidation and rancidiflcationof either animal or vegetable fats or oils. On the contrary; it appears to'have prooxidant properties, but it is usually present in such small proportions that its feeble pro-oxidant value may be neglected for it does not materially affect or reduce the anti-oxidant stabilizing action of the balance of .the resin, from which it is therefore not even separated ordinarily, but allowed to remain with the other component or components,

as'the case may be. However, since it is fluid point, and hence susceptible of different treatment in preparation and in dispersion in fats or oils to be treated with it.

Another effective but notpreferred procedure maybe followed for the recovery of licorice resins from the roots, by treating the m'acerated and extracted licorice roots and fibers with an aqueoim solution of sodium carbonate. The resulting extractive solution is then separated from the solidsandneutralizedwithanacidsuchassulphurlc, whereupon the resin is precipitated and, upon washing with water and preferably after drying. s ready for use. Or, the'-precipitated resin may beobtained in purer condition by dissolving in alcohol, and further, if desired, by separating with benzene, alcohol, petroleum ether, etc as above described.

Itispossibletoeztracttheconstituentsof licorice resin individually by direct treatment of the spent, water-extracted root with the selective solvent. Thus the spent root may first be extractedwithbennenetorecovermebenzene soluble component, and then with alcohol to recover the' alcohol soluble component or with petroleum. ether to recover the petroleum ether the soluble component, followed by an extraction with alcohol.

l brordinarypurposesofstabilizingfatsoroils.

the entire licorice resin as obtained by-the alcohol extraction alone, for example, will be used. But in some cases the solubility relationships between there'sincomponentsandtheoilsorfatstobe treated, or other considerations, may make it preferableto use only one" of the two or three components above described. Again, the oil or fat may itself be used as'the extractant for the spent root, as described below, in which event the relative proportion of the three principal components taken up by the odor fat will depend upon such solubility relationships.- 'fnieammmtoflicoriceresintobeusedasa stabilizer in any given instancejdepends upon various factors such as the degree of stabilization desired, the condition and kind of the fat or oil to be treated, whether the licorice resin is usedassuchorintheform ofoneormoreof its separated components. the degree of effectiveness oftbepartiemarstabilizerwiththe givenfator' oil, and other conditions. As a rule, however, the amount required will be between 0.5% or less and by weight of the substance to be stabilized.

As already indicated, the stablizer may be added to the .fats or oils in various ways. Thus, the stabilizer may be added in its form as licorice resin, after extraction and evaporation of the solvent therefrom, in which instances the -incorporation of the resin with the oil or fat is generally promoted by gentle heating. The stabilizer may also be added and dispersed in the form of the extract solution of the licorice resin,

' the solvent being left in the product or expelled by heating, as desired. In such cases, the solvent should, of course, be of agreeable odor and taste, as with ethyl alcohol. Again, the oil to be stabilized (or the fat if melted) can be filtered through a bed of the spent licorice root, of sumcient depth or for a sufiicient. length of' time or number of times, to take up the desired amount of the fat soluble or oil soluble resin components directly from the spent licorice root.

' The following examples will serve to illustrate typical practical applications of the present invention. For purposes of control, tests were made using an absorption apparatus adapted to shake or agitate the samples in the presence of oxygen. At least two samples were taken for test in each case, onefor a blank and the other or others for treatment with the stabilizer. The time in hours which was required for a ten gram sample to absorb 50 cc. of oxygen at 75 C., or other suitable temperature, is referred-to as the life" of the sample, and furnishes a convenient approximation of the stability in actual use of the fat or oil. Practical taste and odor tests have confirmed the results and conclusions derived from the foregoing accelerated life tests.

Example I A sample of lard was divided into three equal portions. Two of these portions were heated to 100 C. for minutes, one as a control, the other in the presence of 4% by weight of dried spent licorice root. These two heated portions were then clarified and, with the blank, were severally tested for life" as above described. The control suffered a loss-of 40% in life, as compared with the blank, due to the heat treatment. The portion treated with the spent root had a life 145% longer than the control or approximately 45% longer than the blank.

- Ezcample II the others-(portion A). was added the dried bening, in an amount equal to 2% of the weig t of the lard. The life values of'portion A and portion B determined at 100 C.) were found to be respectively 668% and 277% better than the similarly determined life of the blank.

Example III Samples of essential oils were treated similarly, in equal portions, and the life of eachfitermined in like manner, but using a temperature of 75 C. during the tests. For purposes of comparison the results with each oil are given when using the same amount i. e., 1% on the weight of the oil) of the same stabilizer, namely the dried benzene extract of spent licorice root.

The results given under "blank and "treated" in the following table are the life in hours of each sample, determined in the manner already 7 described.

A sample of peppermint oil was divided into two equal portions. One was used as a blank and to the other was added the ethyl-alcohol soluble fraction of the dried spent licorice root resin, in an amount equal to 2% on the weight of the portion. Both portions were tested in the omenabsorption apparatus as above described, at 75 C., and the treated portion showed an. improvement in life of 688%.

As is well known, fats and oils, such as lard, and I the essential oils, which are herein considered and included as examplesof edible oils, frequently vary considerably in quality, due to source, conditions of formation, processing, storage, shipping, etc. Hence results between samples of a given kind of fat or oil will be expected to vary correspondingly. However, the foregoing examples are typical of a number of runs on other oils and fats of the same kinds and hence are representative The plasticity and resinous nature of the licorice resinor of one or more of its segregated components, as above described--also serve in various instances to confer other desirable properties upon various compounds in which it may be used in conjunction with the fats or oils and'other substances.

It should be remembered that this disclosure is by way of illustration and exempliflcation of the present invention only, and that the invention is not limited thereto.

I claim:

1. Method of stabilizing edible fats and oils against oxidation or rancidity, comprising the step of treating the same with one or more of the solid components of licorice resin. v

2. Method of stab lizing edible fats and 0115 against oxidation or rancidity, comprising the step of dispersing in the same one or more of the solid components of licorice resin.

3. Method of stabilizing edible fats and oils against oxidation or rancidity, comprising the step. of dissolving in the same one or more of. the solid components of licorice resin.

4. Method of stabilizing edible fats and oils against oxidation or rancidity, comprising the step of treating the same with the alcohol soluble, benzene insoluble component of licorice resin.

5. Method oi stabilizing edible fats and oils against oxidation or rancidity, comprising the step of treating the same with the alcohol soluble,

benzene soluble component of licorice resin.

6. Method of stabilizing edible fats and oils against oxidation or rancidity, comprising the step of treating the same with the petroleum ether insoluble components of licorice resin.

ageinst oxidation or rancidity, comprising the step of adding anti-oxidant component of licorice resin thereto.

. 10. Method of stabilizing edible fats and 011:

against oxidation or rancidity, comprising the step of adding anti-oxidant component of licorice resin thereto in an edible volatile solvent.

' 11. An edible fat or oil, stabilized against 0&- dation or rancidlty and characterized by having therein an anti-oxidant component of licorice resin.

12. An edible fat or oil, stabilized against oxidation or rancidity and characterized by having therein licorice resin.

13. An edible fat or oil, stabilized against oxidation or rancidity and characterized by having %,Q05,82 therein one or more of the solid coznponents of licorice resin.

14. An edible fat or oil, stabilized against omdation or rancidity and characterized by having therein the alcohol soluble benzene insoluble component of licorice resin.

17. An edible fat or oil, stabilized against oxidation or rancidity and characterized by having therein the alcohol soluble benzene soluble component of licorice-resin.

18. An edible fat or oil, stabilized against oxidation or rancidity, and characterized by having 20 the petroleum ether insoluble components oi licorice resin therein. 

